1. Field of the Invention
The present invention generally relates to the field of industrial control systems and computerized data processing methods and systems. More particularly, and without limitation, the invention relates to data processing methods and systems for use in industrial control.
2. Background Information
Sophisticated industrial processes, such as oil refining, automobile assembly or power generation, require the cooperative execution of numerous interdependent tasks by many different pieces of equipment. The enormous complexity of ensuring proper task sequencing and management, which requires not only procedural logic but constant monitoring of equipment states to organize and distribute operations and detect malfunction, has resulted in the widespread adoption of programmable controllers.
These controllers operate elaborate industrial equipment in accordance with a stored control program. When executed, the program causes the controller to examine the state of the controlled machinery by evaluating signals from one or more sensing devices (e.g., temperature or pressure sensors), and to operate the machinery (e.g., by energizing or de-energizing operative components) based on a procedural framework, the sensor signals and, if necessary, more complex processing. The “inputs” to a particular controller can extend beyond the sensed state of the equipment that the controller directly operates to include, for example, its environment, the state of related machinery or the state of its controllers.
Control requirements become even more complex when different aspects of the same overall process are assigned to remotely situated equipment. Such configurations often require reliable, high-bandwidth, and real-time serial communication links to provide the necessary interconnection and to handle data transfer among controllers and the sensors relevant to their operation.
Ordinarily, process operation is monitored, at least intermittently, by supervisory personnel by means of one or more central management stations. Each station samples the status of controllers (and their associated sensors) selected by the operator and presents the data in some meaningful format. The management station may or may not be located on the same site as the monitored equipment; frequently, one central station has access to multiple sites (whether or not these perform related processes). Accordingly, communication linkage can be vital even in traditional industrial environments where process equipment is physically proximate, since at least some supervisory personnel may not be.
To facilitate the necessary communication, the controller processors and related computers (such as monitoring stations) are arranged as a computer network. A network, basically, is a collection of interconnected computers that use some consistent protocol to communicate with one another. Typically, the network is organized such that any computer may communicate with any other network computer. The communication protocol provides a mechanism by which messages can be decomposed and routed to a destination computer identified by some form of address.
Typically, the various components of such an industrial control system are interconnected by means of a field bus having real-time capability, such as PROFIBUS or real-time Ethernet. Such bus systems have real-time capability in order to guarantee maximum latency times for transmission of control data between the various components of the industrial control system.
U.S. Pat. Nos. 5,805,442 and 6,484,0621 are illustrative of examples for such industrial control systems.